This invention relates to direct contact condensers for use with steam turbines to condense steam drained from such turbines by direct heat exchange between the steam and the liquid coolant.
Generally, direct contact condensers are used very often for steam turbine plants, such as, for example, electric power plants, which are located in areas wherein it is difficult to obtain sufficient cooling water. Direct contact condensers are also used in geothermal power plants in which there is no need to recycle the steam condensate to steam generators. Because the direct heat exchange provides relatively high efficiency in the utilization of the cooling water, it is particularly useful in these aforesaid applications.
In prior art direct contact condensers, steam drained from a turbine enters at the top portion of a horizontally elongated housing and flows downwardly over the full longitudinal length at the widthwise-middle portion of the housing. A baffle member is used to divide and change the direction of this downward flow in generally lateral opposite directions toward the widthwise-end walls of the housing. These lateral flows again generally change direction and travel collectively upwardly over the full longitudinal length of the housing at both widthwise side portions.
These collectively upward flows are made to travel a tortuous path. Streams of cooling water fall in these upward flow zones to cause direct heat exchange. Condensate drops down, is temporarily accumulated in the bottom of the housing, and is then drained along with the cooling water. The noncondensable gases are exhausted from the top portions of the upward flow zones. Such direct contact condensers are disclosed in U.S. Pat. No. 3,575,392.
Improvements have been made to reduce the size of such prior art condensers. These improvements depend on the fact that the downward steam flow, immediately following the entrance, has a relatively high speed such as, for example, 100 meters per second. If cooling water is supplied to such high speed steam flow, the water is converted to a mist which provides good direct contact heat exchange. Accordingly, devices for supplying water to the downward steam flow have been devised.
In this connection, when the load on the steam turbine is reduced, the amount of drained steam therefrom is also reduced. It is necessary in devices having water injection in the downflow stage to stop supplying water to this stage is periods of reduced steam flow, because the kinetic energy of the steam in the upward steam flow stage is reduced due to condensation in the downward flow stage to the point where insufficient kinetic energy is available to obtain good heat exchange efficiency in the collective upward flow stage. Although this problem has been also taken in consideration in the prior art devices, operation of such devices has not been stable, as set forth hereinafter. Such prior art devices are disclosed in Japanese Utility Model Publication No. 3203/79.